Patent GB-551718-A (GB)
Title: Improvements in or relating to the production and use of dyestuffs
IPC: G03C1/12
Filed: 1941-09-01
Abstract: 551,718. Methine dyes, photographic sentitized emulsions. KENDALL, J. D., and MAJER, J. R. Sept. 1, 1941, No. 11139. [Class 2 (iii)] [Also in Group XX] Methine dyes are produced by reacting in the presence of a strong base, a compound of the general formula (where R, is hydrogen or a monovalent substituent group, e.g. alkyl, aryl, aralkyl, heterocyclic, carbalkoxy, or carbalkoxyalkyl, R 2   2  being hydrogen, or a hydrocarbon or heterocyclic group, and R 3  3 is hydrogen or an alkyl or aralkyl group) with an alkyl or aralkyl quaternary salt of a heterocyclic nitrogen compound containing an external reactive methylene group in the α or y position to the heterocyclic quaternary nitrogen atom, or with a corresponding heterocyclic nitrogen base. The methylene group may be in a group -CH 2 -R 4 , where R 4  is hydrogen, alkyl, or aralkyl. The groups R 1  to R 4  may be substituted by hydroxy or amino groups. The heterocyclic nitrogen compound may be derived from substituted or unsubstituted thiazoles, thiazolines, oxazoles, oxazolines, selenazoles, selenenazolines, pyridine, quinoline, indolenine, diazines, e.g. pyrimidine, thiodiazoles, or quinazoline, or the corresponding polycyclic compounds (benzthiazoles, naphthathiazoles, or anthrathiazoles), or the diazines described in Specification 425,609. The strong base may be diethylamine, triethylamine, piperidine, or sodium acetate, and the reaction may be effected in a solvent such as ethyl alcohol. .1 - - Phenyl - 3 - acetic ester - 4 - (1 : : 3 : 3 - trimethyldihydroindolylidene) - ethylidine - 5 - - pyrazolone is prepared by boiling together methenyl - bis - (1 - phenyl - 3 - acetic ester - 5 - pyrazolone), 2 : 3 : 3 - trimethylindolenine methiodide, and triethylamine in ethyl alcohol. 1 - # - naphthyl - 3 - acetic ester - 4 (1 : : 3 - tri - methyldihydroindolylidene) - - ethylidene 5 - pyrazolone, 1 - phenyl - 3 - methyl 4 - (N - methyl - dihydrobenzoxazolylidene) - ethylidene - 5 - pyrazolone, 1 - phenyl - 3 - methyl - 4 - ( N - ethyl - dihydrobenzselenazolylidene) - - ethylidene - 5 - - pyrazolone, 1 - - phenyl 3 - methyl - 4 - (N - methyl - dihydroquinolylidene) - ethylidene - 5 - pyrazolone, 1 - - phenyl 3 - methyl - 4 - (N - methyl - dihydro - indolylidene) - - etheylidene - 5 - - pyrazolone, 1 - phenyl - 3 - methyl - 4 - (N - ethyl - dihydro benzthiazolylidene) ethylidene - 5 - - pyrazolone, 3 - methyl - 4 - - (1 : 3 : 3 trimethyl - - dihydro - indolylidene) - ethylidene - 5 - pyrazo - - lone, 1 - phenyl - 3 - - carbethoxy - 4 - (1 : 3 : 3 - trimethyl - dihydro indolylidene) - ethylidene - - 5 - pyrazolone, 1 - phenyl - 3 - methyl - 4 - - (N - methyldihydrobenzthiazolylidene) - propylidene -  5 - pyrazolone, and 1 - phenyl - 3 - methyl - 4 - (N - methyl dihydrobenzthiazolylidene) - isopropylidene - 5 - pyrazolone are similarly prepared. Compounds of the general formula, in which R 3 is hydrogen, are prepared by heating pyrazolone derivatives containing an unsubstituted intracyclic methylene group in the 4-position with formic acid or with ethyl orthoformate. Compounds in which R 3  3 is other than hydrogen are prepared by heating the pyrazolone or isoxazolone derivative with an appropriate ortho-ester of a monocarboxylic acid, e.g. esters of ortho-acetic acid, orthopropionic acid, or ortho-benzoic acid, in the presence of the corresponding anhydride. Ethyl or other alkyl ortho-esters, or aryl or aralkyl ortho-esters, may be employed. The dyes may be used alone or mixed with other dyes as sensitizers for silver halide emulsions.